1. Field of the Invention
The present invention relates to a process for preparing an organic monomolecular film. In particular, this invention relates to a process for preparing an organic monomolecular polymer film having polyacetylenic, polydiacetylenic or polyacenic bonds, which exhibits electric conductivity and nonlinear optical effects.
2. Description of the Prior Art
Acetylene and diacetylene derivative polymers have electric conductivity because of the presence of a .pi.-electron conjugated system, especially diacetylene derivative polymers have a nonlinear optical effect. Thus, these polymers are useful as optical or electronic functional materials such as optical recording media.
Generally, polymers of acetylene or diacetylene derivatives can be prepared by the polymerization method of Shirakawa et al., using the Ziegler-Natta catalyst. These polymers are obtained in a mass, and thus the direction of the polymerization is not regulated (i.e., the polymers have a three dimensional structure). Therefore, if a thin film is sliced from the polymer mass, the film cannot be an electronic functional material because a long conjugated system of .pi.-electrons is not present in the polymer film. An organic monomolecular film having polyacetylenic bonds is considered to be prepared by a process which comprises forming a monomolecular film made of a straight hydrocarbon chain having an acetylene group on a base plate according to the LB (Langmuir-Blodgett) technique, and then polymerizing the hydrocarbon molecule at the acetylene group with a catalyst.
However, the organic monomolecular films prepared by this process are not stable to heat and ultraviolet radiation. Also, because the films have poor adhesiveness to the base plate, they are susceptible to peeling from the base plate when they are worked. Moreover, the direction of the polymerization of each molecule in the films is not regulated, so that a long conjugated system of .pi.-electron is not present in the film. Therefore these films do not provide optical or electronic functional materials of high quality.